Breathe in, breathe out...

Species name: Pulmonaria officinalis

Common name: lungwort, Our Lady's Milk Drops

Location: Ontario

Lungwort is probably the most common wildflower across all of mainland Europe, where it is native. It exists in every country except for Norway, has been naturalized in Britain, and has spread as far east as Russia and as far south as Iran. It's one successful little plant! Aside from being a wildflower native to Europe, it is also a very common European garden plant which is why it is now found in North America; it was introduced here in the 1700s by European settlers to decorate their gardens and has thrived here ever since. This plant isn't quite successful enough in North America to be considered invasive since it reproduces very, very slowly from seed. Once established, it spreads like a weed through underground rhizomes. We have quite a patch of it growing in our garden. Sure, the flowers are nice and the flower early in the spring when everything else still looks dead, but too much of it is not a good thing. Plus, it's a non-native!

Lungwort is a great example of a principle called the "Doctrine of Signatures". This principle states that if a plant looks like part of the body, it can be used to treat that part of the body. This idea might seem a little crazy (which it is), but this explains where we get a lot of the common names of plants, and even some Latin names: "Pulmonaria" means lungs, and the Latin epithet "officinalis" (or any derivative of that word) means medicine. Any time you see a Latin name of a plant with that epithet, you know it was once used as a medicinal plant (and sometimes still is).

The flowers of lungwort are a great example of "magic" that can happen inside a plant when you're not paying attention. When the flowers first open they are pink, sometimes even almost red. This is because of an anthocyanin-based pigment found in the flowers that reacts to a very low pH by producing a colour that our eyes interpret as pink. As the flower matures, the plant gradually shifts the pH of the flower petals to be significantly more alkaline, sometimes shifting the pH as much as 5-6 points on the pH scale. This causes the anthocyanin pigments to change configuration, and instead of producing a colour that we interpret as pink, our eyes see it as blue. This change in flower colour is similar, yet different to the change in flower colour that can be observed in hydrangeas (which you can read all about HERE). Hydrangeas react to the pH of the soil, which in turn affects the colour of the flowers (as opposed to this flower colour change being plant-directed). The other difference between hydrangea flower colour changes and the changes observed in lungwort is that lungwort is more a direct reflection of the way we think of colour change according to pH: blue means basic, red means acidic. In hydrangea flowers, the colour indicates the opposite (very brightly-coloured blue flowers mean a very acidic soil and bright pink or red flowers mean a strongly basic soil).

So what kind of medicinal uses does this plant actually have? Well, it's currently used as an herbal medicine to treat asthma. This treatment is surprisingly successful; extracts from the plant are now being looked at as an alternative medication to asthma inhalers. Since people with very severe asthma start to notice a "desensitization" reaction occurring with the most commonly prescribed asthma medications, it would be a welcome addition to the market!

The bigleaf of the Hydrangea world

Species name: Hydrangea macrophylla

Common name: Bigleaf hydrangea, hortensia

Location: Ontario

This species of Hydrangea (there are somewhere between 70 and 75 species depending on which authority you consult; even DNA evidence gives two different stories depending on which gene is used to determine species limits) is native to Japan, and there are over 15 common cultivars (over 600 named cultivars in total, although many of these are not common outside of Japan) used in landscaping.

The most unique aspect of this plant (and one of the reasons why it is so widely planted outside of Japan) is the variable flower colour depending on which pH the soil is. It's not the pH directly that contributes to flower colour; it's actually the ability for the plant to take up aluminum ions. There are pigments in the flowers that automatically produce a deep pink or magenta (in some plants this can even be red), regardless of availability of aluminum. If this pigment is not present (and in some cultivars, mutations have been bred into the plant that prevent this pigment from being made), the flowers will be white. At lower pH in the soil, aluminum is more available for the plant to take up into its tissues. When aluminum and the pigment are both present in the petals of the flower, the flower will take on a blue colour. The intensity of this colour is directly proportional to the availability of aluminum to associate with the pigment; the lower the soil pH, the bluer the flower will be. The reverse can be said about higher pH: the higher the soil pH the less available aluminum will be to the plant, and so the pinker the flower colour will be. Towards the middle of the range, around pH 7.0, there is an equal availability of regular non-associated pink pigment, and aluminum-associated blue pigment so the flower appears purple. This concept of "litmus colour change" (where the idea for the litmus paper came from) is backwards from what you would usually think; usually red is a strong acid and blue is a strong base. That's one of the great things about chemistry! Depending on what causes the colour change, the same colour can mean different things under different chemical conditions.

All parts of the Hydrangea macrophylla plant contain trace amounts of cyanogenic glycosides, so consumption of this plant should be done with extreme caution. I would advise against all consumption, but many Asian countries use this plant as a medicinal herb. In Japan it is used to make a tea that is consumed at all times of the year, but in very high amounts around April 8th when it is believed to be Buddha's birthday. In Korea and China, the leaves are also used to make an herbal tea called sugukcha or ilsulcha.